La Grange · ADU cost
What it costs to build an ADU in La Grange, NY
An 800 sq ft accessory dwelling unit in La Grange runs roughly $210k–275k, or about $263–345/sq ft, and that per-square-foot figure sits deliberately above the $215–282/sq ft a full house costs here. An ADU still needs one whole kitchen, one whole bath, its own service panel and its own heating plant no matter how small you draw it, and those costs do not shrink with the floor plan, so they land on half the square footage and push the rate up. Whether the town will let you build one is a separate question from what it costs, and it gets answered parcel by parcel rather than townwide, since the Town of La Grange maps 14 districts that treat accessory units differently from one another, so read the table below as a starting point rather than a verdict.
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ADU cost by size in La Grange
Standard finish, slab on grade, on a flat and clear part of the lot, general-contractor margin included. These are structure costs at Dutchess County pricing, before the service and septic work a second dwelling can trigger.
| Size | Type | $ / sq ft | Estimated total |
|---|---|---|---|
| 400 sq ft | Studio | $349–$457 | $140k–185k |
| 600 sq ft | One bedroom | $292–$382 | $175k–230k |
| 800 sq ft | One bedroom, larger | $263–$345 | $210k–275k |
| 1,000 sq ft | Two bedroom | $246–$322 | $245k–320k |
400 sq ft — One room plus a bath. Garage conversions and small backyard cottages land here.
600 sq ft — The most common detached build - a real bedroom, full kitchen, one bath.
800 sq ft — Room for a proper living area. Still a single bath and one kitchen.
1,000 sq ft — About as large as most codes allow an accessory unit to go.
Why the rate is higher than a house
The systems below are priced for an 800 sq ft unit. The middle column is what each system would cost if it simply shrank with the floor plan; the left column is what it actually costs once you account for the equipment a dwelling needs one of regardless of size. The gap between the two columns is the whole reason small builds price the way they do.
| System | $ / sq ft in an ADU | If it scaled with floor area | Fixed per unit |
|---|---|---|---|
| Site work | $8–$12 | $8 | — |
| Foundation | $17–$24 | $17 | — |
| Framing | $27–$34 | $27 | — |
| Envelope - roof, siding, windows | $34–$43 | $34 | — |
| Plumbing | $29–$36 | $17 | 55% |
| Electrical | $19–$25 | $13 | 35% |
| HVAC | $24–$30 | $15 | 45% |
| Insulation | $8–$10 | $8 | — |
| Interior finishes | $34–$46 | $29 | 15% |
| Millwork & cabinetry | $19–$29 | $12 | 55% |
The fixed-per-unit share is a modeling assumption, not a figure from the code: it is our estimate of how much of each system's budget buys equipment a dwelling needs exactly one of - a kitchen rough-in, a bath group, a service panel, a heating plant - and therefore does not shrink when the unit does. Site work, foundation, framing, envelope and insulation are treated as scaling straight with floor area, which understates the premium slightly, because a small building carries more envelope per square foot of floor than a large one.
What the La Grange code says about accessory units
Whether you can build one, and how large, is decided by the district your parcel sits in rather than by the town as a whole. The table shows how each mapped district treats ADUs alongside the lot and setback standards a second unit still has to fit inside. District boundaries and conditions vary, so treat it as a starting point and confirm the district that applies to your parcel.
| District | Min lot | Setbacks F / S / R | Max height | ADU |
|---|---|---|---|---|
| Residential Flexible-Density | 1.84 ac | 55 / 20 / 20 ft | 35 ft | Special permit |
| Residential Low-Density | 2.75 ac | 55 / 40 / 40 ft | 35 ft | Special permit |
| Residential Moderate-Density | 1.84 ac | 55 / 30 / 30 ft | 35 ft | Special permit |
| Residential Frank & Sleight | — | 35 / 10 / 20 ft | 35 ft | Special permit |
| Town Center Residential | 0.14 ac | — | 35 ft | Special permit |
| Town Park | — | 35 / 100 / 100 ft | 35 ft | No |
| Overlook Planned Development | — | 25 / 100 / 75 ft | 35 ft | No |
| Town Center Business | 0.14 ac | - / 0 / 6 ft | 50 ft | Special permit |
| Hamlet | 0.69 ac | 10 / 5 / 10 ft | 35 ft | Special permit |
| Manchester Gateway Hamlet | — | 10 / 5 / 6 ft | 50 ft | No |
| Gateway Hamlet | — | 15 / 5 / 10 ft | 35 ft | Special permit |
| General Business | 0.92 ac | 40 / 20 / 20 ft | 35 ft | No |
| Commercial | 0.69 ac | 40 / 20 / 20 ft | 35 ft | No |
| Industrial | 1.84 ac | 75 / 20 / 20 ft | 35 ft | No |
Residential Flexible-Density - Minimum lot area depends on utilities: at least 80,000 sq ft on a private well and septic system, 60,000 with either public water or public sewer, and 40,000 with both. At the two smaller sizes building coverage is 15%, and floor area is 30% at 40,000 and 25% at 60,000.
- At 40,000 sq ft the lot need only be 50 ft wide at any point, with 50 ft of Town frontage and 125 ft on a county or state highway; at 60,000 it must be at least 75 ft wide.
- At 80,000 sq ft the lot must be at least 100 ft wide at any point, with at least 75 ft of frontage on a Town right-of-way and 200 ft on a county or state highway.
- On a Town road the front yard must also be 80 ft from the centre line of the road; on a state or county road it is 90 ft.
- A square at least 150 ft on a side must fit on the lot, reducible under the open space subdivision rules at § 240-32.
- Total lot coverage, counting buildings, structures, outdoor deposit and paving, may not exceed 20%.
- Height is also capped at 3 stories.
Residential Low-Density - On a Town road the front yard must also be 80 ft from the centre line of the road, and on a state or county road it is 90 ft. Total lot coverage, counting buildings, structures, outdoor deposit and paving, may not exceed 15%.
- Frontage must be at least 100 ft on a Town right-of-way, reducible to 50 ft on the circular end of a cul-de-sac, and 225 ft on a county or state highway.
- The lot must also be at least 150 ft wide at any point.
- A square at least 200 ft on a side must fit on the lot, reducible under the open space subdivision rules at § 240-32.
- Height is also capped at 3 stories.
- Only finished year-round livable floor area counts toward the minimum, measured inside the exterior walls with a 7 1/2 ft ceiling, and upper floors only where a permanent inside stairway reaches them.
Residential Moderate-Density - On a Town road the front yard must also be 80 ft from the centre line of the road, and on a state or county road it is 90 ft. Total lot coverage, counting buildings, structures, outdoor deposit and paving, may not exceed 20%.
- Frontage must be at least 75 ft on a Town right-of-way, reducible to 50 ft on the circular end of a cul-de-sac, and 200 ft on a county or state highway.
- The lot must also be at least 100 ft wide at any point.
- A square at least 200 ft on a side must fit on the lot, reducible under the open space subdivision rules at § 240-32.
- Height is also capped at 3 stories.
- Only finished year-round livable floor area counts toward the minimum, measured inside the exterior walls with a 7 1/2 ft ceiling, and upper floors only where a permanent inside stairway reaches them.
Residential Frank & Sleight - Development here is part of an open space subdivision under § 240-32, and no further subdivision is permitted. The side yards are 10 ft on one side and 15 ft on the other, at least 25 ft combined, and principal structures must stand at least 25 ft apart.
- On a Town road the front yard must also be 60 ft from the centre line of the road.
- The lot must be at least 60 ft wide at any point, with at least 60 ft of frontage on a Town right-of-way.
- A square at least 75 ft on a side must fit on the lot, reducible under the open space subdivision rules at § 240-32.
- Height is also capped at 3 stories.
- Only finished year-round livable floor area counts toward the minimum, measured inside the exterior walls with a 7 1/2 ft ceiling, and upper floors only where a permanent inside stairway reaches them.
Town Center Residential - The 6,000 sq ft minimum lot applies to a single-family home on public sewers, and the schedule sets no single-family lot area without them. The Planning Board may approve six to twelve dwelling units per acre, and at its discretion a 4,000 sq ft single-family lot.
- A townhouse on public sewers needs 2,500 sq ft, or a 1,650 sq ft lot at the Planning Board's discretion.
- Density may never exceed twelve units per acre overall, and no more than five single-family units on lots under 6,000 sq ft may sit in a row without a break.
- Yards are set in Schedule B4, not on the bulk schedule.
- Total lot coverage, counting buildings, structures, outdoor deposit and paving, may not exceed 60%.
- Townhouses and apartments are excluded from the 70% building floor area limit.
- Height is also capped at 3 stories.
Town Park - On a state or county road the front yard is 100 ft. A square at least 150 ft on a side must fit on the lot, reducible under the open space subdivision rules at § 240-32.
- An apartment needs at least 400 sq ft of floor area.
- Height is also capped at 3 stories.
- Only finished year-round livable floor area counts toward the minimum, measured inside the exterior walls with a 7 1/2 ft ceiling, and upper floors only where a permanent inside stairway reaches them.
Overlook Planned Development - Frontage must be at least 500 ft on a county or state highway. Total lot coverage, counting buildings, structures, outdoor deposit and paving, may not exceed 70%.
- A square at least 200 ft on a side must fit on the lot, reducible under the open space subdivision rules at § 240-32.
- An apartment needs at least 400 sq ft of floor area.
- Height is also capped at 3 stories.
- Only finished year-round livable floor area counts toward the minimum, measured inside the exterior walls with a 7 1/2 ft ceiling, and upper floors only where a permanent inside stairway reaches them.
Town Center Business - The 6,000 sq ft minimum lot applies to a single-family home on public sewers, and the schedule sets none without them. Front yards are set in Schedule B3, and a building must stand 25 ft back from a residential district boundary line.
- The Planning Board may approve six to twelve dwelling units per acre, and at its discretion a 4,000 sq ft single-family lot or a 1,650 sq ft townhouse lot.
- A townhouse on public sewers needs 2,500 sq ft.
- The Planning Board may approve a zero-foot rear yard.
- Total lot coverage, counting buildings, structures, outdoor deposit and paving, may not exceed 90%.
- Height is also capped at 3 stories.
Hamlet - A single-family lot served by public sewers needs 8,000 sq ft rather than 30,000, and a townhouse on public sewers 6,250 sq ft. A building must stand 30 ft back from a residential district boundary line.
- The lot must also be at least 30 ft wide at any point.
- Frontage must be at least 40 ft on a Town right-of-way and 50 ft on a county or state highway.
- Total lot coverage, counting buildings, structures, outdoor deposit and paving, may not exceed 60%.
- Height is also capped at 3 stories.
Manchester Gateway Hamlet - A building must stand between 48.5 and 58.5 ft from the centre line of NYS Route 55, and 25 ft back from a residential district boundary line. A townhouse needs 2,500 sq ft.
- The Town-road front yard does not apply to townhouses and apartments.
- The Planning Board may approve a zero-foot rear yard.
- Total lot coverage, counting buildings, structures, outdoor deposit and paving, may not exceed 85%.
- Height is also capped at 3 stories.
Gateway Hamlet - Height is capped at 2 stories as well as 35 ft, and a building must stand 25 ft back from a residential district boundary line. The Planning Board may approve six to twelve dwelling units per acre.
- A townhouse on public sewers needs 2,500 sq ft.
- On a state or county road the front yard is 10 ft.
- Total lot coverage, counting buildings, structures, outdoor deposit and paving, may not exceed 85%.
General Business - Total lot coverage, counting buildings, structures, outdoor deposit and paving, may not exceed 50%, but where both public water and sewer are available the Planning Board may allow 70% and a 20 ft front yard.
- On a state or county road the front yard is 45 ft.
- A building must stand 30 ft back from a residential district boundary line.
- Frontage must be at least 75 ft on a Town right-of-way and 225 ft on a county or state highway, and the lot at least 50 ft wide at any point.
- A square at least 100 ft on a side must fit on the lot, reducible under the open space subdivision rules at § 240-32.
- Height is also capped at 3 stories.
Commercial - On a state or county road the front yard is 45 ft, and a building must stand 30 ft back from a residential district boundary line. Total lot coverage, counting buildings, structures, outdoor deposit and paving, may not exceed 70%.
- Frontage must be at least 75 ft on a Town right-of-way and 200 ft on a county or state highway, and the lot at least 50 ft wide at any point.
- A square at least 100 ft on a side must fit on the lot, reducible under the open space subdivision rules at § 240-32.
- Height is also capped at 3 stories.
Industrial - A building must stand 300 ft back from a residential district boundary line, and the front yard is 165 ft on a state or county road. Total lot coverage, counting buildings, structures, outdoor deposit and paving, may not exceed 60%.
- Frontage must be at least 100 ft on a Town right-of-way and 200 ft on a county or state highway, and the lot at least 50 ft wide at any point.
- A square at least 200 ft on a side must fit on the lot, reducible under the open space subdivision rules at § 240-32.
- Height is also capped at 3 stories.
Size limits on record in La Grange
Where the code states a size cap, it decides which row of the cost table above actually applies to you. These are the caps recorded for La Grange:
- Residential Flexible-DensityNo more than one bedroom, with floor area of at least 400 sq ft and no more than 35% of the one-family dwelling's entire floor area.
- Residential Low-DensityNo more than one bedroom, with floor area of at least 400 sq ft and no more than 35% of the one-family dwelling's entire floor area.
- Residential Moderate-DensityNo more than one bedroom, with floor area of at least 400 sq ft and no more than 35% of the one-family dwelling's entire floor area.
- Residential Frank & SleightNo more than one bedroom, with floor area of at least 400 sq ft and no more than 35% of the one-family dwelling's entire floor area.
- Town Center ResidentialNo more than one bedroom, with floor area of at least 400 sq ft and no more than 35% of the one-family dwelling's entire floor area.
- Town ParkNo more than one bedroom, with floor area of at least 400 sq ft and no more than 35% of the one-family dwelling's entire floor area.
- Overlook Planned DevelopmentNo more than one bedroom, with floor area of at least 400 sq ft and no more than 35% of the one-family dwelling's entire floor area.
- Town Center BusinessNo more than one bedroom, with floor area of at least 400 sq ft and no more than 35% of the one-family dwelling's entire floor area.
- HamletNo more than one bedroom, with floor area of at least 400 sq ft and no more than 35% of the one-family dwelling's entire floor area.
- Manchester Gateway HamletNo more than one bedroom, with floor area of at least 400 sq ft and no more than 35% of the one-family dwelling's entire floor area.
- Gateway HamletNo more than one bedroom, with floor area of at least 400 sq ft and no more than 35% of the one-family dwelling's entire floor area.
- General BusinessNo more than one bedroom, with floor area of at least 400 sq ft and no more than 35% of the one-family dwelling's entire floor area.
- CommercialNo more than one bedroom, with floor area of at least 400 sq ft and no more than 35% of the one-family dwelling's entire floor area.
- IndustrialNo more than one bedroom, with floor area of at least 400 sq ft and no more than 35% of the one-family dwelling's entire floor area.
Costs an ADU adds that a house does not
- Septic and water A second dwelling adds bedrooms to the design flow, which on an unsewered parcel often means expanding or replacing the existing system rather than tapping it. This is the single most common reason an ADU budget moves after design, and it is site-specific enough that no model should quote it - get it evaluated early.
- Utility service Central Hudson territory. A detached unit needs power run to it, and whether it goes on its own meter or subfeeds the main house changes both the cost and the permit path.
- Access and parking Many codes require an added parking space for the accessory unit, and a detached unit usually needs a driveway extension or a path, both of which count against a lot-coverage or impervious-surface cap.
- Short-term rentalsNo local short-term-rental law on record - which is not the same as permission. The Town of La Grange has no local short-term rental registration law as of Jun 2026, and that is not the same as permission. Confirm with the Town of La Grange Building Department before counting on short-term rental income. Separate question from whether you can build the unit.
- Zoning codeecode360.com/6412940
- Building dept(845) 452-1830
Sizing up a specific parcel in La Grange?
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Building a full house instead?
A standard-finish house in La Grange runs $215–282/sq ft, about $390k–510k at 1,800 sq ft , plus roughly $4,495 for a conforming lot. See what it costs to build a house in La Grange.
ADU cost in nearby towns
All Dutchess County towns: Beacon (City) · Poughkeepsie (City) · Amenia · Beekman · Clinton · Dover · East Fishkill · Fishkill · Hyde Park · Milan · North East · Pawling · Pine Plains · Pleasant Valley · Poughkeepsie · Red Hook · Rhinebeck · Stanford · Union Vale · Wappinger · Washington · Fishkill (Village) · Millbrook (Village) · Millerton (Village) · Pawling (Village) · Red Hook (Village) · Rhinebeck (Village) · Tivoli (Village) · Wappingers Falls (Village)
More on La Grange: Can you build an ADU here? · Zoning for new construction · Dutchess County build cost
ADU cost in La Grange: common questions
How much does it cost to build an ADU in La Grange, NY?
An 800 sq ft accessory dwelling unit in Town of La Grange runs roughly $210k–275k at a standard finish, general-contractor margin included. A 400 sq ft studio runs about $140k–185k. Those are structure costs on an easy site and do not include the septic, water or electrical service work a second unit often triggers.
Why does an ADU cost more per square foot than a house in La Grange?
Because a lot of a dwelling's cost is per dwelling, not per square foot. One kitchen, one bath group, one service panel and one heating plant cost about the same in an 800 sq ft cottage as in a 1,800 sq ft house, so on the smaller unit they get spread over less than half the floor area. That is why an ADU here prices at $263–345/sq ft against $215–282/sq ft for a full house, even though it is the same trades doing the same work.
Are ADUs allowed in La Grange?
Town of La Grange has 14 districts. 8 districts allow ADUs with a special-use permit, 6 do not. Check the specific address with the free ADU checker or confirm with the building department at (845) 452-1830 before you spend money on design.
Can I rent an ADU in La Grange short term?
No local short-term-rental law on record - which is not the same as permission for Town of La Grange. ADU rules and short-term-rental rules are set separately, so a unit you are allowed to build is not automatically one you are allowed to rent nightly. Confirm both before you underwrite the build on short-term-rental income.
ADU costs are modeled estimates in current 2026 dollars at the Dutchess County regional index, general-contractor margin included, derived from Offsite's cost engine with a stated adjustment for the equipment a dwelling needs one of regardless of size. They are planning numbers for decision-support only - not a bid, quote, or guarantee, and not legal, architectural or engineering advice. They cover the structure and exclude septic expansion, utility service runs, site work beyond a flat and clear pad, and permit fees. ADU eligibility, size, owner-occupancy and permit conditions in the Town of La Grange vary by district and often carry exceptions this page does not show; zoning last reviewed 2026-08-16; verify with the building department at (845) 452-1830 before relying on any answer. Sources: the Offsite / Aldo cost engine and zoning dataset.